Ultrasonic plastic welding (UPW) is a promising technology for joining metal to carbon fiber reinforced thermoplastic composite (CFRTP) but shows poor joint strength in the existing studies. This ...work conducts UPW of AA6061 aluminum alloy to carbon fiber reinforced PA66 (CF/PA66) by employing a polymer coating as an interlayer. Simple metal surface grinding and silane coupling agent (SCA) treatment are used to strengthen the bonding of the metal/coating interface. Structured CF/PA66 surface fabricated by ultrasonic embossing acts as energy directors to improve the bonding strength of the coating/plastic interface. The results show that relatively high tensile-shear strength (about 31.0 MPa) can be obtained. Micro-mechanical interlocking and chemical bonding (Al-O-C and Al-O-Si bonds) are considered as the bonding mechanism of the metal/coating interface.
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•Al/CFRTP was successfully joined by UPW by preparing a plastic coating on the metal surface.•Ultrasonic embossing is used to prepare energy directors in an efficient and cost-effective way.•The optimal joint strength reaches to 31 MPa which is significant higher than the existing research.
•Phononic crystal is introduced in large-sized tools for the first time.•The radial wave cannot propagate due to the periodic grooves.•The displacement distribution is improved due to suppressing the ...lateral vibration.
Large-sized tools are needed for plastic welding of large objects. However, the displacement distribution at the radiation surface of the tools is not uniform due to the strong lateral vibration. In this paper, two-dimensional (2D) phononic crystal (PnC) is introduced by processing periodically arranged grooves in large-sized tools. This method is different from the traditional experience-based grooving method. The lateral vibration is suppressed due to the characteristic of PnC. In this paper, six kinds of ultrasonic plastic welding systems based on 2D PnC with different groove width and height are designed. The vibration characteristics of ultrasonic plastic welding systems were simulated and experimented. The band gaps of large-sized tools are analyzed. The results show that the lateral vibration is suppressed when the operating frequency of the ultrasonic plastic welding system is within the band gap of the large tool. The displacement distribution at the radiation surface of the tools is more uniform. A theoretical support is provided for the design of large-sized ultrasonic plastic welding systems.
In this paper, an experimental investigation on diode laser transmission welding of dissimilar thermoplastics between PMMA (polymethyl methacrylate) and ABS (acrylonitrile butadiene styrene) has been ...carried out. The effect of the laser welding parameters such as laser power, welding speed, stand-off distance and clamp pressure on weld strength and weld width is investigated using response surface methodology (RSM). Planned experiments and subsequent analyses are carried out to develop the mathematical models to establish the correlation between the process parameters and the responses. The adequacy of the developed models is tested using the sequential F-test, lack-of-fit test and the analysis-of-variance (ANOVA) technique. A numerical multi-objective simultaneous optimization technique, in which the RSM is incorporated, is used to find the optimum solutions, according to the desired optimization criteria. In addition to that, a graphical optimization technique is, also implemented which allow identifying a region in the graphic where optimal conditions lay on.
► Laser transmission welding of dissimilar thermoplastics between PMMA and ABS has been experimentally investigated. ► RSM is applied to the experimental data to relate the laser welding parameters with the responses. ► The effect of welding parameters on the responses is studied on the basis of the developed models. ► The mathematical models are further used to find optimum welding conditions to achieve the desired weld quality.
This article presents a novel approach for the electrical interconnection of embroidered conductive yarns with each other at defined cross-points using ultrasonic spot welding. The electrically ...conductive yarns are made of silver-coated copper microwires plied with polyester filament fibers into a hybrid embroidery yarn. In this study we evaluated the influence of different material properties (number of microwires of conductive yarn, fabric substrate, and adhesive film), the embroidery designs of contact pads, and the main parameters of the welding process (energy, force, amplitude, and tools) on the welded interconnection. The results were evaluated by the process yield and the contact resistance of the welded contacts. The electrical contacts were then tested for long-term reliability (elevated temperature and humidity, temperature shock change, bending, washing and drying) and analyzed. In addition, the contacts were examined with scanning electron microscopy (SEM) and micro-computed tomography and in the form of cross-sections with optical and SEM techniques to discuss interconnection and failure mechanisms. The results show that ultrasonic spot welding can enable the production of highly reliable interconnections of textile-integrated conductive yarns with contact resistances of a few milliohms that are resistant to mechanical, environmental, and washing conditions, leading to potential new manufacturing processes of e-textiles.
•Meltdown has 4 phases: induction, transient, steady-state and cooling.•Meltdown depends linearly on total line energy (power x number of scans/speed).•Increasing scan length increases critical total ...line energy for meltdown to begin.•Simple mathematical model captures the main elements of meltdown.
Meltdown is the term used to describe the collapse of two thermoplastic parts during welding. It is a critical process parameter in the laser-transmission welding of thermoplastics. This study examines the effect of quasi-simultaneous (QS) laser transmission welding (LTW) processing parameters including input power (P), number of passes (N), scan speed (V), total scan length (LS) and weld pressure on the meltdown behavior of polycarbonate (PC) and polypropylene (PP), using a T-shaped test assembly. The total meltdown is shown to depend linearly on the total line energy (LET) defined as the product of P and N divided by V. Increasing LS increases the critical LET for meltdown to begin. A simple model is presented that captures the main elements of meltdown in this thermoplastic welding process.
This paper presents a three-dimensional finite element model (FEM) of laser transmission welding of dissimilar plastics. Welding of polycarbonate to ABS (acrylonitrile butadiene styrene) with a ...moving volumetric heat source is modeled using ANSYS
®
Parametric Design Language. In model development, consideration is given to all major thermal phenomena associated with the laser transmission welding process, such as heat conduction, convection, and thermal radiation. The model also incorporates the effects of dilution on temperature cycles. Welding experiments are conducted to validate the numerical model. The model predicted simulation results are in good agreement with the measurements. The results predicted by the model can further be used for the optimization of the process.
Vulcanization of polypropylene Houghton‐Flory, Callum; Saed, Mohand O.; Terentjev, Eugene M.
Journal of polymer science (2020),
1 May 2024, 2024-05-00, 20240501, Volume:
62, Issue:
9
Journal Article
Peer reviewed
Open access
Dynamic covalent crosslinking of commodity thermoplastics is a desirable target in material development, as it promises to combine the enhanced mechanical properties and thermal/solvent stability of ...thermosets with reprocessability and plastic flow under certain conditions activating the bond exchange. Many attempts of this development suffer from the same two problems: enhanced cost due to complex and often toxic chemicals, and the effective melt‐flow index being too low for practical use. Here we return to the origins of polymer networks, and mimic the vulcanization of natural rubber in the commodity polypropylene using elemental sulfur initiated by peroxide. Forming sulfur bridges allows easy catalyst‐free reprocessability based on the disulfide bond exchange. We study a broad range of compositions and reaction conditions, finding optimal balance between the crosslinking and chain scission in the melt compounder, and demonstrating much enhanced characteristics of the resulting materials. We specifically discuss and evaluate the balance between the rubber‐elastic network response at high temperatures and the plastic flow enabled by disulfide exchange, responsible for the reprocessing of our vitrimers.
High-performance polyamides (HPPA) matrix composite meets the demanding requirement of automotive thermal management applications as a replacement to conventional metals. Effective joining of such ...composites are still a challenge and a better understanding of material performance upon joining are needed. This research study investigates the behavior of glass filled semi-crystalline and partially aromatic polyamide composite upon ultrasonic plastic welding. Welding process parameters were experimentally realized for a quality weld in shear type joint configuration. A weld strength of 3.1 kN was achieved. Material performance, thermal transition, degradation temperature, mass loss and morphology near welding zone were evaluated by advanced characterization techniques. A decrease in glass transition temperature (Tg) and change in material crystallinity were observed. The morphology of welded interface reveals minimum void formation. Negligible amount of weight loss was observed after welding with a degradation temperature much higher than material melting point, suitable for high temperature applications.
